I'm looking for a couple of pictures showing rocker arm position with valve fully open and closed using different rocker arms.My engine builder is curious to see how they compare to the Harland Sharp rockers that I currently have on the engine?

Can anyone help me out with this?

Cheers,

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

Here you go. This is a cam with about .480 lift and the hyd lifters are lashed down so the would show full lift. The pushrod is not the perfect size and could have been slightly longer.Rockers shown are my old rocker CompCams, Harlan Sharp, and my Current Comp offering.

With the lower speed misfire and poor performance the engine builder took the engine back and did a few things.We installed a new MSD distributor to rule out any ignition issues.

Back onto the engine dyno and rewarded with pretty good even power up to 6,000 RPM.Peak HP = 257 @ 5,800 RPM. Peak torque = 270 @ 4200 RPM. (we are not tuning for power, just mechanical issues)

The problem is when we hit 6050 RPM! All hell breaks loose!

It's as if a crude rev limiter kicks in and a destructive misfire event occurs. I accept the fact that 500 RPM past peak HP the power curve is dropping but the engine should still be able to run fairly well.

Here are a couple of links to show what is going on. The one from the control room is using my phone as a camera, but listen carefully as the tach hits 6K. (Headphones help)Ugly noise.The second video shows misfire through the carb and then the timing marks.

Here is a short summary that was sent to Comp Cams to get their input.______________________________________________________________________________This engine (chev I6 250cid) was on the dyno last year, and had very erratic curves, and the engine would not rev up clean after about 4800 rpm. Saw that the valve tips were getting a "star" pattern after only a few pulls, so the decision was made to increase spring rate and pressure. Went to an Isky295D spring (140 - 360 pressure, up from 120-330). This helped a bit, gaining about 400 RPM. Seemed to like near zero lash (hyd cam).

Engine went back to the builder, and a tried a few things for round 2.

Limited the hyd plunger travel down to about .025 (running the plunger down about .010).

Swap to a dual LS type 1.290 OD PSI spring, 160 - 390... in an effort to change the harmonics from a single with damper type spring.

Put it on the dyno yesterday and the curves look much smoother, power is up about 20, and engine runs clean to 6050 - 6100 RPM, and then hits a wall. Take a rocker off after two pulls and see a pattern again on the tips, tho faint, but it is only after very little time.

Rockers are Harland Sharp 1.70

Pushrods are Manton 3/8 OD x .120 wall (right around 10.125 OAL)

Lifters are (what I assume to be) the comp hard bottom hyd lifters, now with limited plunger movement to about .025.

Engine is being run NA right now (will be turbocharged once in the car.. just proving engine now).

ANy thoughts come to mind here? Attaching a few pics and the cam card. Cam (X 8754-12) was purchased by the customer and supplied to the engine shop that built it.

On the graph, the blue is HP and green is TQ, it falls off right after 6000 rpm on that pull.

I am using Walt's damper. Both my engine bulider and the guy running the dyno do no see that as a suspected problem based on the information in front of them.I did ak about it when I was at the dyno room on Tuesday.

P

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

Specs on the engine, for a quick view here. Parts, intake manifold, carb spacer, carb size, jetting , plug gap, what distributor, (standard HEI module, new, used, modules do not always just work or do not work, they can still work but give lousy spark, I know this first hand), coil, plug wires, ohms on plug wires,(even new plug wires can be bad, same goes for plugs.

I had a new set of Champion plugs & would miss every once in a while & took the longest time to figure out what the miss was coming from, found the ceramic porcelain collar was sliding down & covering up the spark plug gap.

The video seems to be like a not completely flat camshaft but a wearing camshaft, popping back through the carb.

Ignition problems @ higher RPM, not burning the fuel causing the fuel to back fire through the carb.

Ignition is my new MSD distributor and the MSD box and coil from the dyno. Known good as he was spinning up a small block to 8,400 RPM on Monday and no issues.

I will find out about the plugs. Pretty sure I have them on one of the invoices (there are many).

Clifford intake, 650 CFM Holley carb. Not sure of the jetting but can find out. Same with A/F. I think it was running a little fat but wull check. The print out I brought home did not show the correct A/FDyno fuel pump. Sheet says 6.3 lbs fuel pressure.Compression 9.1:1Lumped heads.

Thanks for the help guys.

P

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

Just looked at the video again and I would bet it too lean and it's a lean pop, the engine is at full throttle long before the RPM starts to climb, then small pops from the rear, could be just too strong of a spring and takes a lot of RPM to open the butterflies.

Timing was 33ish. Timing did not effect it, nor did air fuel ratio changes with jetting. "

The cam is making power at 5,800 so no issues there. If it would behave itself on the downside just to 6400 or 6500 I would feel safe boosting it.It is the sudden change to a very unhappy engine that is problematic.

Seat pressure with the current springs is 160/390. With lighter springs the condition is happening at much lower RPM.

Maybe my expectations with this cam are out to lunch but we all have a gut feeling that something else is going on.

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

Clifford intake, 650 CFM Holley carb. Not sure of the jetting but can find out. Same with A/F. I think it was running a little fat but wull check. The print out I brought home did not show the correct A/FDyno fuel pump. Sheet says 6.3 lbs fuel pressure.Compression 9.1:1Lumped heads.

Thanks for the help guys.

P

[/quote]

What type of fuel pump are you using? Maybe??? not enough fuel flow? Just because the pressure looks good does not always mean you have enough flow.

fuel pump is same dyno pump used to feed bigger and more powerful engines before and after my engine.

The balancer is Walt Pearce's unit. They are supposed to be known to spin over 6K without issues. I believe you had one at high revs Tom?

I hear ya on all the basics Hank. The guy running the dyno is a well know engine builder that does a lot of high revving circle track engines.

I will pass on everyones comments to the engine builder.

I have taken a very laid back approach to the engine as I had a lot of work to do to the car before it would be engine ready. Now I am pretty well caught up on the other work and would like to have the car on the road in July.

I told the engine builder to come up with a solution and costs associated by the 27th.

Paul.

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

Larry,The Dyno loads the engine and holds it back from revving. Then they start the pull. The Dyno then let's the engine pull the rpm's up at a determined rate of climb. Like 200 rpm per second or 400 rpm per second.

Don't crawl back into any holes there Turbo 6! Your input is valuable.

I'm curious what other people are running for timing gear on their turbo 6 engines? What kind of power you are making at what boost.

I am going to get together with the builder and dyno guy and have a chat about next steps. Frustrating because I am so close to having an engine that is ready for boost and install.

Tuning for HP etc. will be done on the chassis dyno.

Engine builder is Muscle Motors in Strahmore Alberta. They have a pretty good reputation building high power engines. Dyno guy is Ryan Brown Performance. He too brings a lot of engine experience to the table.

I am confidant that they will make this little inline happy.

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

I have a customer with a 292 and that same cam. He only turned it to 4800 rpm on a engine dyno. 450HP and 497 ft lbs tq. The tq was still peaking at 4800. I suspect his boost was also creeping. He said it was 12 PSI.

The SBC Chevy one I used is a 300 HP 350CI SBC 8" damper.You would need to make brackets & pulley changes to make it work, a lot of work I.M.O.Their are no V-grooves for belts on SBC dampers.I was desperate to get my 250 to turn past 5500 RPM so I improvised & installed a SBC damper.

So finally got the engine back on the dyno with it's new cam and lifters.Revs well past 6,000 RPM now and power curve is very good.Without tuning for anything it made 246 HP @ 5900 and 249 ft/lbs at 4,300 RPM.The good part is that it did not fall flat on its face at 6,000 RPM. It was able to rev to 6,700.

Car is out getting turbo exhaust and intercooler fabrication work done then time to put the engine in the car.

Will post some progress pics soon.

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

I am planning on using Eldon Cottingham. He is no longer in Calgary so it means a trailer road trip to BC interior. Eldon has been helpful in this process and he has tuned a lot of well known and powerful cars. Who were you thinking of Marc?

Funny thing Hank about your recommendation, i called Cambell Automotive way back when I started down this path. They were not interested. Too busy they said. I heard that they have since closed that business and it is now Moretto. Not really sure about that but since there was no interest from Campbell's I never kept up to date with the shops north of me.

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.

I know Toma and yes he is very good. Not sure what your issue is with Eldon, but everyone I know has had great success with him.

One thing this last go 'round proved is that Walt's balancer is indeed capable of meeting the needs of my engine. Tom's cam made great power and is more than sufficient of meeting the needs for most engines.

That's the fun thing about this hobby. Learning!!

Paul

_________________________
V8 camaros are like navels,...everybody has one. EFI Turbo 250 project well under way.